The present invention relates in general to feeding tabbed sheets from a stack of tab stock, and more particularly to an apparatus for handling tab stock in a top feed vacuum corrugated feeder.
In typical reproduction apparatus such as copiers or printers, for example, information is reproduced on individual cut sheets of receiver material such as plain bond paper or transparencies. Receiver sheets, of the various types, are stored respectively in a stack and fed seriatim when copies are to be reproduced. The sheet feeder for the reproduction apparatus must be able to handle a wide range of sheet types and sizes reliably and without damage. Sheets must be accurately fed individually from the sheet stack, that is, without misfeeds or multi-feeds.
One recently described highly efficient and reliable sheet feeder is shown in U.S. Pat. No. 5,344,133, issued Sep. 6, 1994, in the name of Jantsch et al. In such apparatus, a stack of sheets is stored in a supply hopper. A sheet feed head assembly, including a plenum, a vacuum source in flow communication with the plenum, and a mechanism, such as a feed belt associated with the plenum, urges a sheet acquired by vacuum in a sheet feeding direction away from the sheet supply stack. The sheet supply stack is supported so as to maintain the topmost sheet in such stack at a predetermined level in spaced relation with respect to the urging mechanism of the sheet feed head assembly. A first positive air supply directs a flow of air at the sheet supply stack to levitate the top several sheets in the supply stack to an elevation enabling the topmost sheet to be acquired by vacuum from the sheet feed head assembly plenum; and a second positive air supply directs a flow of air at an acquired sheet to assure separation of any additional sheets adhering to such topmost sheet.
With the advancement in the operative capabilities of reproduction apparatus, it has been desired to expand the types of receiver material which can be utilized in the reproduction apparatus. One of the expanded types of receiver material desired to be used is the type referred to as tab stock. Tab stock includes sheets having an even edge and an opposed uneven edge with a projection spaced along such uneven edge. The projection (tab), which for example can serve as a location for a label (pre-printed or printed by the reproduction apparatus), enables the sheet to separate or provide divisions in a copy set. Due at least in part to the projections, typical reproduction apparatus receiver sheet feeders have some difficulty in reliably feeding tab stock. While the feeder of the above described type reliably handles a wide variety of standard individual cut sheets of receiver material, it also does not readily accommodate tab stock.